Heat exchanger with rolled-in capillary for refrigeration apparatus

ABSTRACT

A FLUID FLOW STRUCTURE WHEREIN A FIRST FLUID FLOW DUCT IS PROVIDED WITH AN EXTERNAL, OUTWARDLY OPENING GROOVE. THE GROOVE IS COVERED BY AN OUTER ELEMENT WHICH, IN THE ILLUSTRATED EMBODIMENT, COMPRISES AN OUTER TUBE. THE GROOVE IS MADE TO BE SMALL IN CROSS-SECTION SO AS TO DEFINE A CAPILLARY RESTRICTOR RELATIVE TO FLUID FLOW THERETHROUGH. THE RESTRICTION OF FLOW IS ADJUSTED BY SUITABLY DEFORMING THE OUTER TUBE OVERLYING THE GROOVE SO AS TO ADJUSTABLY DECREASE THE CROSS-SECTION OF THE CAPILLARY RESTRICTOR PASSAGE. THE FLUID FLOW STRUCTURE MAY BE USED IN A REFRIGERATION SYSTEM FOR PROVIDING HEAT EXCHANGE BETWEEN REFRIGERANT FLUID DELIVERED FROM THE EVAPORATOR THROUGH THE FIRST TUBE AND REFRIGERANT FLUID DELIVERED FROM A CONDENSER TO THE EVAPORATOR THROUGH THE CAPILLARY PASSAGE.

March'Z, 1971 RQEDER, JR 3,566,615

HEAT EXCHANGER WITH ROLLED-IN CAPILLARY FOR REFRIGERATION APPARATUSFiled April 5, 1969 f J9 J6 I 24 jnUenZ 07": Jo/zw/ Raeder; J2,

United States Patent HEAT EXCHANGER WITH ROLLED-IN CAPILLARY FORREFRIGERATION APPARATUS John Roeder, Jr., Benton Harbor, Mich., assignorto Whirlpool Corporation Filed Apr. 3, 1969, Ser. No. 813,187 Int. Cl.Fb 41/06 US. Cl. 62-511 10 Claims ABSTRACT OF THE DISCLOSURE A fluidflow structure wherein a first fluid flow duct is provided with anexternal, outwardly opening groove. The groove is covered by an outerelement which, in the illustrated embodiment, comprises an outer tube.The groove is made to be small in cross-section so as to define acapillary restrictor relative to fluid flow therethrough. Therestriction of flow is adjusted by suitably deforming the outer tubeoverlying the groove so as to adjustably decrease the cross-section ofthe capillary restrictor passage. The fluid flow structure may be usedin a refrigeration system for providing heat exchange betweenrefrigerant fluid delivered from the evaporator through the first tubeand refrigerant fluid delivered from a condenser to the evaporatorthrough the capillary passage.

BACKGROUND OF THE INVENTION Field of the invention This inventionrelates to fluid flow structures and in particular to heat exchangerssuch as used in refrigeration apparatus.

Description of the prior art In conventional refrigeration systems,restriction of the flow of refrigerant to the evaporator is provided bymeans of a capillary duct having a small cross-section. Further, thecapillary duct is connected through a heat exchanger to the evaporatorwith a heat exchanger defining a duct for delivering refrigerant fromthe evaporator for subsequent recycling. A conventional method ofadjusting the capillary restriction is to vary the length of thecapillary tube. Such a method of adjusting the restriction has theobvious disadvantage of requiring disconnection and reconnection of thecapillary restrictor after determining a need for such adjustment.

Another problem found in the conventional refrigeration systemstructures is the space requirements for providing separate capillaryand heat exchanger devices arranged in series in the system. The knowndevices further have the disadvantage of relatively high cost.

SUMMARY OF THE INVENTION The present invention comprehends an improvedfluid flow structure which eliminates the disadvantages of the abovediscussed known structures. More specifically the present inventioncomprehends a fluid flow structure including wall means defining a flowpassage, the wall means further defining an outwardly opening groove ofsmall cross-section, a cover element overlying the groove and sealed tothe wall means, the overlaid groove defining a second fluid flow passageproviding capillary restriction of fluid flow therethrough, meansdefining an inlet to the second flow passage, and means spaced from theinlet defining an outlet for the second flow passage.

Further, more specifically, the invention comprehends the provision ofsuch a fluid flow structure for use as a heat exchanger in arefrigeration system having an evaporator and a condenser, the heatexchanger comprising a first tube, means for connecting the first tubeto the evap- Patented Mar. 2, 1971 "ice orator for conductingrefrigerant from the evaporator, the wall of the first tube having anindented small crosssection groove therein, a second tube encircling thefirst tube and covering said groove whereby the covered groove defines acapillary passage, and means for connecting the capillary passagebetween the condenser and the evaporator for conducting refrigerant fromthe condenser to the evaporator, the first tube being formed of athermally conductive material whereby refrigerant being deliveredthrough the capillary passage is cooled by refrigerant flowing throughthe first tube.

The invention comprehends adjusting the restriction provided by thecapillary restrictor by suitably deforming the outer cover element so asto project inwardly into the groove. The deformation of the coverelement can be readily effected after assembly of the fluid flowstructure and by the simple expedient of rolling a groove in the coverelement overlying the groove of the inner tube, the depth of therolled-in outer groove being controlled to provide the desired increasedrestriction of fluid flow through the covered groove.

In the illustrated embodiment, the inner tube or duct and outer coverelement comprise concentric cylindrical tubes having a relatively snugfit with the groove in the inner tube being helical and with suitableinlet and outlet structures provided in the outer tube to permit flow offluid therethrough.

BRIEF DESCRIPTION OF THE DRAVVI NGS Other features and advantages of theinvention will be apparent from the following description taken inconnection with the accompanying drawing wherein:

FIG. 1 is a diametric section of a fluid flow structure embodying theinvention in a portion of a refrigeration system including an evaporatorand a condenser;

FIG. 2 is a transverse section thereof; and

FIG. 3 is a fragmentary diametric section of the fluid flow structureillustrating the arrangement thereof as adjusting for providing apreselected capillary restriction.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the exemplary embodiment ofthe invention as disclosed in the drawing, a refrigeration systemgenerally designated 10 is shown to comprise a fluid flow structuregenerally designated -11 defining a heat exchanger for providingprecooled refrigerant liquid to an evaporator 12 from a condenser 13.The liquid refrigerant is cooled by heat exchange with the refrigerantdelivered from the evaporator !12 flowing in counter-current flowthrough the heat exchanger 11.

As discussed above, the fluid flow'structure 11 is extremely simple inconstruction while providing the highly desirable heat exchange betweenthe liquid refrigerant delivered to the evaporator and the refrigerantdelivered from the evaporator which may be in the form of vapor andpurge liquid. As best seen in FIG. 1, the fluid flow structure 11comprises a first tube 14 having an inlet end 15 and an outlet end 16.The tube is defined by wall means provided with an indented groove 17,which in the illustrated embodiment, is helical and extends fromadjacent inlet 15 to adjacent inlet 16. The tube 14 is preferably formedof a material having high thermal conductivity such as metal andillustratively may be formed of steel, brass, aluminum, etc. The groove17 may be formed in the tube 14 as by a conventional rolling processwell known to those skilled in the art. The cross-section of the groove,as shown in FIG. 1, is relatively small as compared with thecross-section of the tube 14.

Concentrically surrounding the inner tube 14 is a second or outer tube18 which may have a relatively snug fit with the inner tube, and whichdefines a cover element overlying the groove 17. The covered groovethusly defines a capillary restrictor passage 19. As shown in FIG. 1,the end of the tube 18 may be welded to the inner tube 14 adjacent inlet15 and the end 21 of the tube 18 may be welded to the tube adjacent theoutlet 16 whereby the tube 18 effectively sealingly covers the groove 17to define the capillary passage 19.

The outer tube 18 may be provided with an opening 22 defining an inletopening to the capillary passage 19. A suitable connector 23 may besecured to the tube at opening 22 for delivering refrigerant from thecondenser 13 to the capillary passage 19. A similar opening 24 isprovided in the opposite end of the tube 18 to define an outlet openingfor delivering the refrigerant from the restrictor passage 19 through anoutlet connector 25 to the evaporator 12.

As the inner tube 14 is formed of a material having high thermalconductivity, heat exchange readily occurs between the refrigerantflowing through the restrictor passage 19 to the evaporator and therefrigerant flowing from the evaporator through the inner tube 14. Thus,the refrigerant being delivered to the evaporator 12 is precooled forimproved efficiency of cooling in the evaporator. Illustratively, therefrigerant may comprise liquid ammonia where the refrigeration systemcomprises a conventional absorption refrigeration system.

Thus fluid flow structure 11 is extremely simple and economical ofconstruction while providing the highly desirable dual function ofprecooling of the refrigerant being delivered to the evaporator andproviding capillary restriction thereof for control of the fluidpressures in the system.

The fluid flow structure provides a further advantage over theconventional fluid flow structures in such refrigerator systems in thatadjustment of the restriction of flow from the capillary passage 13 maybe readily effected by simple deformation of the outer tube to cause atleast a portion thereof to project into the capillary passage 19, asshown at 26 in FIG. 3, whereby the crosssection of the flow passage 19is adjustably reduced to a desired preselected value. The deformation ofthe outer tube may be substantially along the entire length of thepassage 19 or may be at preselected portions thereof as desired. Wherethe passage is helical, the deformation may comprise a helical groovesubstantially coincident with the passage 19. The deformation may bereadily provided in the outer tube 18 as by a conventional rollingoperation.

Thus, at least a portion of the passage 19 comprises a capillaryrestrictor in heat exchange relationship with the refrigerant deliveredfrom the evaporator. Accurate control of the amount of restriction isreadily obtained in the improved simplified fluid flow structure byvirtue of the readily controllable deformation of the outer tuberelative to the groove 17.

The invention has been illustrated in connection with a refrigeratorsystem wherein the fluid flow structure comprises a heat exchanger forcontrolling refrigerant delivered to and from the evaporator. As will beobvious to those skilled in the art, the fluid flow structure 11 mayequally well be utilized as an evaporator having integral capillarypassage means, as well as other similar heat exchanger arrangements.

Having described my invention as related to the embodiment' shown in theaccompanying drawings, it is my intention that the invention be notlimited by any of the details of description, unless otherwisespecified, but rather to be construed broadly within its spirit andscope as set out in the accompanying claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. A refrigerant fluid flow structure comprising: wall means defining afirst refrigerant fluid flow passage, said wall means further definingan outwardly opening groove of small cross-section; a cover elementoverlying said groove and sealed to said wall means, the overlaid groovedefining a second refrigerant fluid flow passage having an accuratelypreselected configuration providing a preselected capillary restrictionof fluid fiow therethrough, said cover element facially engaging saidwall means over a major portion of the confronting surfaces thereof;means defining an inlet to said second fluid flow passage; and meansspaced from said inlet defining an outlet for said second flow passage.

2. The fluid flow structure of claim 1 wherein said cover elementdefines an inwardly projecting portion extending adjustedly into saidgroove to provide a preselected adjusted restriction of the fluid flowthrough said second fluid flow passage.

3. The fluid flow structure of claim 1 wherein said wall means is formedof thermally conductive material providing high heat transfer betweenfluids flowing through said first and second fluid flow passages.

4. The fluid flow structure of claim 1 wherein said wall means comprisesa first tube, and said cover element comprises a second tubeconcentrically encircling said first tube.

5. The fluid flow structure of claim 1 wherein said groove comprises ahelical groove.

6. The fluid flow structure of claim 1 wherein said second flow passagehas a substantially constant crosssection throughout its length wherebysubstantially the entire second flow passage comprises a capillaryrestrictor.

7. In a refrigerator system having an evaporator and a condenser, a heatexchanger comprising:

a first tube;

means for connecting the first tube to the evaporator for conductingrefrigerant from the evaporator, said first tube having an indentedsmall cross-section groove therein;

a second tube surrounding said first tube and covering said groovewhereby said covered groove defines a capillary passage;

and means for connecting said capillary passage between said condenserand said evaporator for conducting refrigerant from the condenser to theevaporator, said first tube being formed of a thermally conductivematerial whereby refrigerant being delivered through the capillarypassage is cooled by refrigerant flowing through said first tube.

8. The heat exchanger of claim 7 wherein said groove comprises a rolledgroove.

9. The heat exchanger of the claim 7 wherein said second tube isadjustably deformed into said groove to provide adjustable flowrestriction of said refrigerant being delivered to said evaporator.

10. The heat exchanger of claim 7 wherein said second tube is adjustablydeformed into said groove along substantially the entire length of saidgroove.

References Cited UNITED STATES PATENTS 1,797,014 3/1931 Nichols 1561,957,828 5/1934 Greenwald 62-5l1 2,145,774 1/1939 Muffly 625133,468,371 9/1969 Menze 165-l56 MEYER PERLIN, Primary Examiner US. Cl.X.R.

